Color photography



Patented Jan. 6, 1942 COLOR PHOTOGRAPHY Michele Martinez, London,England, assignmto Eastman Kodak Company, Rochester, N. Y.

No Drawing.

This invention relates to color photography. Broadly speaking two wayshave long been known for producing images corresponding to the variouscolor sensations of nature, namely:

(1st) By producing the images of different color sensations at difierentdepths of a layer or of superimposed layers of light sensitiveemulsions:

(2nd) By producing such color images in minute separate juxtaposed areasof a single light sensitive layer or a plurality of such layers.

The two systems have been variously utilised to produce colorphotographs, the first in what has been called the subtractive methodand the second in what has been called the additive method, of colorphotography.

This invention provides new materials and means for color production inboth systems, the second of which, however, is no longer utilised on theadditive principle but is made to produce subtractive multi-colorpictures.

Organic compounds have long been known which, acting on silver halidesalts exposed to light, yield colored oxidation products alongside withsilver images. In some cases the developer alone produces the coloredimage whilst in other cases it requires an additional compound, referredto herein as a color former. Many of the colored products or dyestuffsproduced belong to wellknown groups, characteristics of which areindophenols, indamines, indoanilines, azomethines, oxazines,indothiophenols and others and their ring-system products, their nuclearand side-chain homologues and substitution products,

- are to provide means whereby the action of color formers can belocalised relative to the emulsion so that the colors produced therebydo not diffuse from the original positions of the color formerparticles; also to provide means whereby the speed of penetration ofdevelopers into an emulsion can be controlled, and hence their actionscan be limited to definite regions in the emulsions.

Application October 3, 1938, Serial In Great Britain October 5, 1937 22Claims.

The present invention is not concerned with any special chemicalcomposition of the color formers, developers, emulsions or othermaterials although it may employ some of the improved materialsdescribed in the present applicants United States of America patentapplication Ser. No. 226,381. Neither is it concerned whether the colorsare produced in the parts of layers exposed to light or, after reversal,in the parts of the layer not originally exposed, or again whether thereis one layer of emulsion or two or three or whether they are coated allon one side or distributed between the two sides of a support. Thedesired localisation is obtained in a purely physical way in a mannerwhich can be controlled.

According to the present invention the action of a color former islocalised by means of a resin or gum resin, associated with the colorformer or, when the color former is in the developer, with the emulsion.

In one form of the invention the material is adapted to record difierentcolor sensations in difierent layers. In this case either a color formermay be incorporated in a layer and. associated with a resin or gum resintherein, or alternatively the resin or gum resin may be arranged betweenlayers of emulsion and serve to act as a resist to the action of thedeveloper on the layer beyond. In the latter case also a color formermay be incorporated in at least one layer.

In an alternative form of the invention the material is adapted forproducing a colored image composed of numerous minute specks or grainsof two or more different colors and includes different particles foreach color to be produced, each particle including a color former with aresin or gum resin to localise its action and in addition a colorfilter. The particles may also include appropriate sensitisers.

Both forms of the invention operate on the subtractive principle, thatis to say in the finished picture only those colors which are notdesired are removed from the light, as opposed to the additive principlecustomarily employed in connection with mosaic or screen pictures inwhich all except the required primary colors are removed from the lightand the desired color is obtained by synthesising such primary colorsemanating from neighbouring areas of the picture.

A further feature oi. the invention is the employment of particles asdescribed for the production of one or more colors and the employmeritof the interstices between such particles for the production of afurther color.

The invention includes the improved photographic sensitive material andalso the process of preparing it. The latter preferably includes forminga solution of a resin and a color former in a common solvent andapplying the resulting mixture of resin and color former to a sensitiveemulsion either by mixing it with the emulsion before coating on asupport or by applying it to the surface of the emulsion after thelatter has been coated on to its support.

The invention also includes the process of developing the improvedmaterials. This may in some cases be performed by employing developersappropriate to the color formers in the ordinary way. Alternatively fora photographic material containing resins of progressively decreasingsolubility in alkali in or between successive layers of emulsionintended to record different colors, successive layers may be developedwith developers appropriate to the colors of the layers and ofprogressively increasing alkalinity. Thus the resin will act as a resistto the action of the developer whilst the first layer is developed, butthe subsequent employment of a developer of increased alkalinity willdissolve the layer of resin and allow the developer access to the nextlayer of emulsion.

Similarly for a photographic material incorporating a plurality ofdifferent color formers associated with different resins ofprogressively decreasing solubility in alkali, developers ofprogressively increasing alkalinity may be employed appropriate to theseveral color formers. Thus there will first be employed a developer ofminimum alkalinity appropriate to the color former associated with theresin which is most readily soluble, followed by developers ofincreasing alkalinity appropriate to the color formers associated withresins of decreasing solubility.

A further feature of the invention is the employment of what may bereferred to as a color and black method of development for aphotographic material intended to record one color sensation in asurface layer and another in a deeper layer. This includes firstdeveloping with a mixture of a black developer and a color developercontaining but little alkali sulphite to form a black surface image anda deeper colored image, bleaching the black image and redeveloping inanother color. Further details and explanation of this method will begiven hereafter.

Certain specific examples. will now be described.

In the first example to be described the sensitive material is adaptedto record different color sensations in different layers and hasdifferent color formers in the different layers each associated with aresin or gum resin to localise its action.

This may be effected by dissolving the color formers in a non-aqueoussolvent together with a natural or synthetic resin or gum resin, such ascolophony or gum mastic, or the like, then mixing such solution, littleby little while stirring, with a light sensitive emulsion of with anaqueous solution of a colloid, such as gelatine, for addition to anemulsion.

The result is that resin and color former are suspended in the emulsionin fine dispersion of particles in each of which is present both resinand color former, physically attracted to each other by their commonwater-repellent property.

.It is a wellknown fact that resins have marked adhesive properties,which also contribute to the localisation of the reaction. There is awide range of resins, both natural and synthetic, for any volatilesolvent and of various solubility in alkali, from those which require avery small quantity of a carbonate to those that require greateralkalinity up to that of caustic hydroxide, so that any can be chosenwhich will resist the action of a developer of given alkaline contentfor the desired time.

Besides the resins mentioned, namely colophony and gum mastic, othernatural resins and gum resins available include shellac, sandarach,dragon's blood, dammar, and others, while synthetic resins may be thecondensation products of formaldehyde or phenol alcohols with phenols,oxy-, aryloxy-, or alkyloxy-carboxylic acids or phenoxy fatty acids;also such synthetic resins which may further be treated with halogenfatty acids or the condensation products of phenols or phenol-carboxylicacids with aliphatic, aromatic, or heterocyclic aldchydes orthionlychloride.

When a solution of a suitable resin or gum resin is mixed with asolution of a color former and dispersed in an emulsion, it acts, in away, as a resist to the action of developer preventing the colorformerfrom migrating to other layers, while it does not prevent colordevelopment, which, however, is strictly localised to the silver halideadjacent to each particle. For instance, if an emulsion is made tocontain particles as described and, for demonstration purposes, theseare very widely scattered, and is then developed in the appropriatecolor developer, only the parts where the particles are present aredeveloped in .color, yielding an image formed of little dots,

the interstices between particles remaining colorless. If. on the otherhand, a black developer is instead applied, it acts only in theinterstices between particles; and subsequently, if desired, a colordeveloper can be applied, which will only act in the parts whereparticles are present.

It is clear that the quantity of particles can be such as to give such aclose formation as will leave no interstices between particles, onebeing always present over or under interstices to close up any gap.

As an example, a 5% solution of colophony in acetone or gum mastic inalcohol and acetone is made, and of this 5 to 10 c. c. are taken, and

gm. 0.50 of a color former, such as alpha naphthol, or gm. 0.25 of suchagent as p-nitro benzyl cyanide is dissolved in it.

The solution is then mixed either directly in 100 c. c. of a dilutedsilver halide emulsion or in 40 c. c. of a 7 or 8% gelatine solution,which is afterwards added to c. c. of silver halide emulsion. The coloryield by the color formers in such conditions is so abundant that theemulsion can well stand dilution as mentioned, but may be used ingreater density if desired.

It is easily understood that one, two or three layers of emulsions canbe coated on one side or distributed between the two sides of a support,each layer containing a localised color former for one of the two orthree main color sensations, so as to produce colored pictures accordingto accepted principles of subtractive color photography. Separationlayers are not strictly necessary, unless they may be required for color111- tering purposes. The layers may be suitably and differently colorsensitised, or, if the material is to be utilised for positive making inaccordance with the co-pending patent application referred treatments.

to above, at least one of them need not be color sensitised.

If it is desired to develop one color at a. time or one separately fromthe others, then color formers may be chosen which require difierentdevelopers; or else two or more resins or gum resins, natural orsynthetic, are chosen, which are soluble in different quantities orstrengths of alkalies; and development in successive operations iseffected with different developers or with solutions of different alkalicontent, as required by the resins employed.

The resins may either be incorporated in the layers of emulsion oralternatively they may be in separating layers which may also containlight filters or sensitisers. In either case the layers contain eitherprogressively decreasing quantities of resin from the support to theouter surface of the emulsion, or else differentresins of increasingsolubility in alkali. The firstdeveloper for one color may contain avery weak alkali and in a specified time will only act on the firstresin layer. For the next layer a developer for a different color andmore strongly alkaline is needed in order to dissolve away the firstresin layer and act on the second layer. Any subsequent developers will,of course, have increasing alkali contents, each sufficient to act ononefurther resin layer. In this manner successive layers can bedeveloped in different colors, the color formers being incorporatedeither in the appropriate developers or resin layers.

color former which gives one color with one developer and another withanother developer. any such color may be developed de ending on the kindof color rendering desired. for instance whether in direct or incomplementary color or Whether reversal is applied or otherwise. In thecase of alpha naphthol. it can give blue with di- It is also found thatin many ca s e when selective developmentis desired. an amidoldeveloper. or the old ferrous oxalate developer which requires no alkalinor sulphite, are quite efiective for the. production of a blackstratum.

In a general way resins retard the penetration of developers. thusprolonging time of treatment, but this, far from being a drawback. isdesirable for control of efiects and f r selective They also have theadvanta e of rendering the materials better able to withstand alkali oracid treatments such as acid fixing and reversal processes.

In some instances it may be desirable to incorporate localised colorformers .only in one or two of the lower layers and apply color andblack development as briefly referred to above so that at least the topcolor may be produced ina sec- 0nd operation, such procedure allowingcontrol of the top color, which is desirable, especially when this topcolor is to be the blue record. This color and black developmentconstituting one feature of the present invention allows a coloredstratum to be produced at a depth that can be adjusted almost at will sothat it can be made to coincide with the divisions between layers ofemulsion, if any, or be limited approximately to the depth penetrated byrays of one color, preferably also permitting the formation of at leasttwo stratifications in one single treatment or operation.

The underlying principle of the color and black method is as follows.When color formers are employed to develop a photographic surface incolor, there is necessarily produced alongside with the dye image acertain amount of black reduced silver. This amount of silver isdependent inter alia on the quantity of alkali sulphite present in thedeveloping solution. The function of the sulphite in ordinarydevelopers, referred to herein as black developers, is well known; beingavid of oxygen, the sulphite cornbines with it as it is evolved ondecomposition of the silver halide, and thus prevents the developeritself from being oxidised and hence rendered inactive in a very shorttime. In color development the sulphite is no longer necessary, moreoverit is a handicap as it would prevent the oxidation of the developer,which in this case is desired to produce a dyestufi. Hence very littlesulphite is used in color development, generally from two grammes tofour grammes per 1000 c. c. of solution, or as little as necessary toimpart contrast to the dye image.

Color developers are very slow in their action as compared to blackdevelopers and in any case there is a wide range of black developersfor. one to be chosen that is very rapid in comparison to any colordeveloper that it may be necessary to use. Thus if a small quantity of arapid black developer is combined in suitable proportions with a largerquantity of a slower color developer, in the presence of a smallquantity of sulphite, the black developer acts quickly almost alone onthe first strata of a photographic material under treatment but isquickly oxidised and rendered inert while the color developer continuesin its action on the lower strata: thus there is obtained in the upperparts of the material a practically pure silver image and in the lowerparts a practically pure dye image. .The silver ima e can then bebleached and on a second development in another color, the latter isproduced in place of the first developed image. The second de velopmentcan also be again one combined of .black developer and color developeras in the first instance, in which case three color strata willultimately be obtained.

The relative quantities and speeds of black developer and colordeveloper and the quantity of sulphite can be so adjusted that thestratification of black and of color can be obtained, in a given time,for an emulsion or emulsions of given resolving power, practically atany desired depth.

As an example, the following solutions are prepared: (a) Sodiumcarbonate, anhydrous, gm. 40, potassium bromide gm. 2, water c. c. 960.(b) Metol gm. 0.75, sodium sulphite anhydrous gm. 1 1, hydroquinone gm.1.50, water 0. c. 250.

(c) Diethyl-p-phenylene diamine hydrochloride gm. 2, sodium sulphiteanhydrous gm. 4, water 0. c. 100.

(d, p-Nitro benzyl cyanide gm. 0.50, acetone c. c. 10, methyl alcohol 0.c. 30, water 0. c. 10.

For use, take (a) 40 c. c., (b) 5 c. c., (c) 5 c. c., (d) 2 to 3 c. c.

This will give equal depth stratiflcations of black and red on a twolayer material, but, of course, the proportions vary in accordance withthe characteristics of the emulsions. The various solutions can becompounded differently, and reduced to two stock ones to the sameeffect.

In similar manner stratifications of two colors or of two colors andblack can be obtained, in the case of two colors by choosing twodevelopers and color fromers which are of different rapidity and ofwhich one is compatible with the presence of larger quantity of sulphitethan the other.

Glycin is a very good black developer for use in treatments in thismanner, and so also pamido phenol as a black developer. In some casesthe solution may contain potassium bromide as it is well known that someblack developers resent its presence strongly and some very little, andthe same has been found to be true of color formers. It is impossible togive rigid rules and formulae due to the number of different colorformers available quite apart from variations in the degree of purity ofindividual compounds. The precise quantities can be ascertained by trialfor any given color former and quality of emulsion.

Addition of small quantities of a fixing agent, such as sodiumthiosulphate, to the compounded solution, contributes to the formationof pure black stratifications, while addition of potassium ferrocyanidehelps the formation of pure color in the relative stratum.

The invention may also be employed in conjunction with photographicmaterials which contain color formers incorporated in fine dispersion inor between emulsions. For instance, if a color former is present in alower stratum of emulsion or in two lower strata of emulsions andanother or other upper layers are not provided with such agents, thenthe treatment previously described acts even better, the color formerbeing, of course, omitted from the compounded solution.

If two color formers are distributed in two different layers ofemulsions they may be chosen of different propensity to oxidation, so asto give rise automatically to the characteristic results of mytreatment. Black developer can still be incorporated in the compoundsolution, for production of silver image in a third top layer. Or again,with one color former in the lowest only of three layers, a compoundsolution can be made of a black developer, the color developer requiredby the color former present in the material, and another color former offaster action with its own color developer if necessary, when in oneoperation two colored layers and one of black silver are obtained.

Finally, it is obvious that a color that is produced in second operationin place of black silver firstly developed, can be obtained by othermeans than color development, for instance by toning, dye toning, dyedestruction and. so forth.

In another form of the invention the .material is adapted for producinga color image composed of numerous minute specks of two or moredifferent colors and includes different particles for diflerent colorsto be produced. 'A feature of the invention is the production of afurther color in the interstices between the particles.

In this application of the invention the wellknown principles of mosaicand screen filter formations are employed in'conjunction with thelocalisation method referred to above to produce multi-colored picturesnot by the additive but by the subtractive system.

Each particle comprises a resin or gum resin, a color former, a coloringmatter to act as a filter. and if necessary a color sensitiser. Theseare dissolved in a volatile solvent such as alcohol, acetone, xylene, ormixtures of these substances. The solution may then be added to asolution of gelatine or any other suitable medium for addition to anemulsion, or else direct to an emulsion. The particles remain suspendedin the emulsion and may act as color filters to the material beneaththem. On development the exposed particles produce colored areas, thewhole forming a multi-color image. The colors of the original particlesmust always be removed, either by decoloration or solution in thedeveloper, or by a subsequent treatment.

The colored particles may contain color formers which either produce adyestufl of the same color as the filter, orof its complementary color.

The area or mosaic effect does not ultimately appear, owing to a. slightcolor diffusion round each particle.

Such color particles may be utilised in a photographic material invarious ways of which the following are examples.

Whenever henceforth reference is made to one particle the expression isintended to mean a number of localised particles of one color with theappropriate color former, and similarly two particles and "threeparticles" are intended to mean particles for producing two colors andfor producing three colors respectively.

1. A single panchromatic emulsion contains in fine dispersion two orthree colored particles intermixed in due proportions. If there happensto be any small gap between particles or if there is any silver halidenot provided with any of such particles or over any of them, no harm isdone because in those parts only black is produced which is finallyremoved. Color development is applied with the requisite developer ordevelopers in a single operation, or, if desired, when the color formerscall for more than one developer, in simultaneous or successiveoperations, with final removal of all colorfilters, silver, and silverhalide. If desired, each particle may be made to contain also therequired sensitiser.

2. Only two colored particles (of localised and colored color formers)are dispersed in an emulsion, which may contain a general filter toserve for the third color: the emulsion may be panchromatic or onlysensitive to the one color the agent for which or for the complementaryof which is not provided in particle form. In the latter case the twoparticles carry their. appropriate sensitisers. The third color isdeveloped in the interstices between the two particles, either byapplying color-and-black development as previously described, or byadding the third color former, and if necessary its color developer, tothe developing solution. If desired, successive treatments can beapplied instead, first developing the interstices in black, and thendeveloping the colors. Ultimately all color filters, silver halide andsilver are always removed.

3. Two emulsions are utilised, one plain or containing colored orcolorless particles for one color, and the other containing one or twoparticles for another or other colors. Simultaneous development of allcolors or separate developments can be applied, as in previous cases,with the same final removal. The interstices between particles of bothemulsions can be made to produce another color.

4. Three localised colored particles, with or without sensitisers, aremixed in a weak solution of a colloid or other binding agent and coatedin a thin layer over a silver halide emulsion.

Treatment is in one operation or in successive operations as desired,always with final removal as mentioned.

5. Three particles as in the preceding case can be formed over oneemulsion, without binding agent or medium other than theresin or gumresin that is utilised. Various methods can be followed: for instanceeach of the three color formers is dissolved in a solvent and with aresin or gum resin and with a coloring matter different from the other,choosing such resins and coloring matters as will not dissolve in thesolvent of the other: the three solutions may be mixed and applied orsprayed over the photographic surface in one operation or may beindividually applied in successive operations: as the solvents, atleast, are different, a second application will not interfere with theprevious one. On volatilisation of the solvents, three particles areleft adhering to the surface. The treatments are as before, with thedifference that the particles can ultimately all be quickly eliminatedby application of a mixture of these solvents or of a solvent common toall. The particles may be only two, the third color being produced inthe interstices.

6. Two or three particles are emulsified in plain water, with addition,if desired, of a little glycerine, plastifier or the like, and areapplied, coated or sprayed over the photographic material.

7. Two or three localised particles as in previous cases are suspendedin aluminium hydroxide jelly freshly prepared and are coated over anemulsion. The same treatments are used. The

overlayer can be removed in due time with a solvent for the aluminajelly.

8. Two or three particles again as before are suspended in an easilysoluble medium other than a colloid: for instance in cellulose acetatedissolved in benzole: such a medium is easily dissolved finally inalcohol or in a mild acid such as lactic. Again, the treatments are thesame.

9. Two or three particles as before are produced, dried, finely powderedand applied or blown, on to a photographic surface just moistened orthinly overcoated with an adhesive or colloid layer still wet. Again thetreatments are the same.

10. When two localised particles only are coated, produced, or appliedover an emulsion, as in previous cases, the third color can be developedin the interstices, as has been specially mentioned in certain cases.

11. One emulsion contains particles for one color, and two otherparticles for two other colors are coated, produced, or applied over theemulsion, the first color contained in it being developed through theinterstices between the overlayed particles. The treatments are as inother cases.

12. This example is similar to the preceding one, with the differencethat particles for one color only are overlayed: the third color beindeveloped in the interstices between the overlayed particles. Very closecolor formation is thus obtained, the treatments being as' alreadydescribed.

13. Two emulsions are utilised, one containing particles for one colorand particles for two other colors or for another color being applied,produced, or coated over the whole. Treatments are similar to those usedin similar cases.

14. One or more particles can be formed of color former and coloringmatter alone, without resin, finely powdered and then suspended in aresin solution, more especially of an artificial resin, which isafterwards applied in a thin layer over the emulsion as a lacquer orvarnish. Other varnishes, for instance, of benzyl cellulose, or anyother suitable type, may be used.

15. Forms other than mosaic may be adopted in any of the examples given:for instance, screen or pattern, or lines in one direction or crossways:such formations can be produced mechanically by means of rollers and inany other suitable way. These applications are obvious and need not bespecially described.

16. One particular method of forming a two color screen of particles inan easy way consists of first applying very thinly on a photographicsurface a mixture of water and alcohol or water and other volatilesolvent: .the surface then is made to pass under a mild blow of hot airwhich volatilises such solvent leaving minute globules of water: insteadof this procedure, water vapour uniformly applied can serve the purpose.In the case of mixtures of water and a volatile solvent, the proportionsof the two determine the size of the ultimate grain: one part of waterand two of volatile solvent answer most purposes. Immediately afterwardsthere is applied thinly over the surface a solution of resin with colorformer and dye for color filter all in a volatile solvent. This will dryquickly in very minute particles, and soon afterwards again a watersolution of another water-soluble color former, with another sensitiserif necessary and with other coloring matter for filter, alwayswater-soluble, is applied, which will only remain in the intersticesbetween the particles first formed. Production of a third color may becaused in the inside of the emulsion.

Many other formations are possible, as those skilled in the art willreadily understand, and two or more kinds of natural and syntheticresins and gum resins and solvents or other resists can be made use of,for selective treatments as described.

Thesemosaic or part-mosaic like materials are best utilised for makingmulti-color positives, more especially on paper supports.

When one or two particles as described are suspended in an emulsion orbetter still are produced or coated over the same so as to leave smallclear interstices or line spaces in between them, if a sensitiser isthen applied in a solution which also contains water, it acts almostsolely in the interstices or line spaces, and thus selective part areasensitisation can be achieved: or else, or at the same time, anothercolor former in solution containing water can be applied, thus attainingalso a very close formation of color formers.

It is further found that particles as described for one or more colorscan be emulsified in a water solution of tragacanth gum, say 0.50 or 1per cent, and coated over an emulsion. Such a layer will remain firmlyin place for so long as may be required and after treatment is is easilyremoved physically by very slight rubbing while wet or with a squeegee.

Layers or formations of one or more particles as described can be madealso between or under light sensitive layers; when'between, they alsoserve as separation layers; and, if carried by a medium, the latter maybe made to contain a supplementary color filter.

In a variation, particles in mosaic form or lines, of one or morecolors, are made to contain only the color filter and resin as resist,without color former; and then successive developments in color or blackcan be applied; for instance first in black with little or no alkali,which will act in the interstices or line spaces, then with a colordeveloper with such alkali or solvent as will attack one of the resinsonly, and so forth. Or, in the case of particles or lines of one coloronly with spaces between, first black or one color may be developed inthe spaces, then the particles or lines of resist are removed in asolvent, and another color development is applied which can only act inthe areas uncovered: color former for a third color may be contained,localised or otherwise, in the emulsion or in a lower emulsion, and becontemporarily developed both or either in first and second treatment.

Materials in which an emulsion is overcoated with lines or dots of onecolor and spaces or other lines in another color may be utilised toimpress thereon a pair of stereoscopic pictures, one of the pair beingfiltered in a color and the other in another color so that the lines ofone color reproduce, say the left view and the others the right view,when stereoscopy alone or stereoscopy in colors may be obtained insuitable viewing or projecting arrangements.

Finally, specially when particles are to be applied without a binder ormedium over one emulsion, it may be expedient to form or lay theparticles first on a temporary support, when, in full lightingcircumstances and without danger of damaging an emulsion, they may bearranged to perfection, and then transfer the formation on to thephotographic material by bringing them into contact, the photographicmaterial being previously moistened or coated with a thin colloid oradhesive layer.

What I claim as my invention and desire to secure by Letters Patent is:

1. A photographic gelatino silver halide sensitive material havingdifferent color formers incorporated in differently color-sensitiveregions thereof, characterised in that each color former is associatedwith, but not chemically combined with, a resin to localise its action.

2. A process of preparing a photographic sensitive material whichincludes forming a solution, but not a chemical combination, of a resinand a color former in a common solvent and mixing the resulting mixtureof resin and color former with a sensitive emulsion.

3. A photographic gelatino silver halide sensitive material havingdifferent light-sensitive layers incorporating different color formersadapted to record different color sensations, at least one color formerbeing associated with, but not chemically combined with, a resin tolocalise its action.

4. A photographic sensitive material adapted for producing a coloredimage composed of numerous minute grains of at least two differentcolors, including different particles for different colors to beproduced in contact with a lightsensitive emulsion, each particleincluding a color former, a color filter and a resin to localise theaction of the color former.

5. A photographic sensitive material according to claim 4. in which theparticles of at least one color include also an appropriate sensitiser.

6. A photographic sensitive material according to claim 4, in whichparticles of at least one color are incorporated in the body of anemulsion.

7. A photographic sensitive material according to claim 4, in whichparticles of at least one color are applied to the surface of anemulsion.

8. A photographic sensitive material according to claim 4, in which atleast two layers of emulsion containing said particles are employed.

9. A process of making a sensitive photographic material for producing acolored image composed of numerous minute grains of at least twodifferent colors, which includes incorporating in contact with a lightsensitive emulsion different particles for the several colors to beproduced, each particle including a color former, a color filter and aresin to localise the action of the color former.

10. A process of producing a photographic sensitive material, whichincludes dissolving a resin and at least one color former capable offorming a dye selected from the group consisting of indophenolsindamines, indoanilines, azomethines, oxazines and indothiophenols in anonaqueous solvent and mixing them with a light sensitive emulsion.

11. A process of producing a photographic sensitive material, whichincludes dissolving a resin and at least one color former in anonaqueous solvent, adding them to an aqueous solution of a colloidalmaterial, and adding the latter to a light sensitive emulsion.

12. A process of producing a photographic sensitive material, whichincludes dissolving a natural resin and at least one color former in anon-aqueous solvent, adding them to an aqueous solution of a colloidalmaterial and adding the latter to a light-sensitive emulsion.

13. A process of producing a photographic sensitive material, whichincludes dissolving a natural resin and at least one color former in anon-aqueous solvent, adding them to an aqueous solution of gelatin andadding the latter to a light-sensitive emulsion.

14. .A process of producing a photographic sensitive material, whichincludes mixing with a light sensitive emulsion a plurality of solutionseach including a color former, an appropriate color filter and a resin.

15. A process of producing a photographic sensitive material, whichincludes adding to an aqueous solution of a colloidal material aplurality of solutions each including a color former, an appropriatecolor filter and a resin, and mixing the colloid solution with a lightsensitive emulsion.

16. A process of producing a photographic sensitive material, whichincludes coating on the surface of a light-sensitive photographicmaterial a plurality of solutions each of which includes a resin, acolor former and an appropriate color filter.

17. A process of producing a photographic sensitive material, whichincludes coating on the surface of a light-sensitive photographicmaterial a water emulsion of a plurality of different color particleseach including a resin, a color former and an appropriate color filter.

18. A process of producing a photographic sensitive material. whichincludes coating over the surface of the light-sensitive photographicmaterial a suspension in aluminium hydroxide jelly of a plurality ofdifi'erent color particles each including a resin, a color former and anappropriate color filter.

19. A process of producing a photographic sensitive material, whichincludes coating over the surface of alight-sensitive photographicmaterial a suspension in a solution of a cellulose ester of a pluralityof different color particles each including a resin, a color former andan appropriat color filter.

20. A process of producing a photographic sensitive material, whichincludes forming a plurality of powders each consisting of particlesincluding a color former, an appropriate color filter and a resin andapplying such dry powders to the surface of a light-sensitivephotographic material which has beentreated so as to cause them toadhere to it.

21. A process of producing a photographic sensitive material, whichincludes forming a plurality of powders each consisting of particlesincluding a color former and an appropriate color filter, suspendingsuch powders in a resin solution and applying the latter as a varnish tothe surface of a light-sensitive photographic material.

22. A photographic process for treating the material claimed in claim 8,which includes exposing and color-developing it, and decolorising thecolor former of the particles subsequent to exposure.

MICHELE MARTINEZ.

CERTIFICATE OF CORRECTION. Patent No 2,269,158. January 6, 19142.

' nIcnEp MARTINEZ.

It is hereby certified that errorappears in the'printed specificatiqn ofthe above nmnh ered patent requiring correction as follows: Page 7,second column, line 15, claim 22, fer the claiin reference mnneral "8"read -11."; and that the said Letters Patent sheuld be read with thiscorrection therein thet the same mav conform to the record of the casein the .Patent Office Signed and sealed this 5rd day of March, A. D.191;.2.

- Henry van Arsdele, (Seal) Acting Commissioner of Patents.

